A claim that GM technology is helping deliver higher crop yields in Africa was wrong, the Government's chief scientist has been forced to admit.

Professor Sir David King recently caused uproar with his assertion that GM crops could help feed the hungry of the Third World.

He called on the Government to campaign for the adoption of GM technology and said the Daily Mail's campaigning stance against it was holding up progress.

Yesterday however he was accused of 'letting off blasts of hot and sometimes rancid air' after it emerged his latest GM crop claims were wildly innaccurate.

Dr Richard Horton, the editor of medical journal The Lancet said Sir David took his faith in science into 'the realms of totalitarian paranoia'.

Writing in his online blog he said: 'If he lost the debate on GM, it was because his arguments failed to convince people.

'King seems biased and even antidemocratic. It seems he would prefer the media not to exist at all. That is a troubling position for the Government's chief scientist to adopt.'

Critics of Sir David suggest he has become 'demob happy' following his decision to stand down.

Since the announcement, he has taken a more outspoken line on controversial issues such as GM, global warming and the need to innoculate children with the MMR vaccine.

Dr Horton said Sir David was 'letting off blasts of hot and sometimes rancid air to relieve the dyspeptic frustrations of seven years in the most uncomfortable job in science'.

The chief scientist had used the example of crop trials around Lake Victoria in Kenya to boast how useful GM farming could be in feeding the Third World.

He claimed scientists had discovered the identity of a chemical in food plants that attract pests such as root borers.

Sir David suggested it had been possible to 'snip' the gene responsible for this chemical out of the food crop and then insert it into grass that is grown alongside it. He said the pests then eat the grass rather than the food.

He told Radio Four's Today programme: 'You interplant the grass with the grain and it turns out the crop yield goes up 40-50 per cent. A very big advantage.'

The only problem is Sir David failed to accurately describe the research in Africa, which did not involve the use of any GM technology at all.

The research actually involved finding plants that can be cultivated alongside food crops and provide a natural solution to boosting yields.

Researchers identified one set of plants that naturally deters parastic weeds, while another set, a species of grass, attracts the pests.

The net result of this 'push and pull' regime is that the food crop can grow more easily and produce a much higher yield.

Green pressure groups are demanding a public apology from Sir David, whose credibility has been shaken by the error.

Director of the GM Freeze campaign, Pete Riley, said: 'We find it quite staggering that Professor King made such misleading comments.

'The 'push pull' project in fact illustrates how the problem pest and weeds which plague farmers in the Global South can be tackled by well researched crop management techniques.

'These have the advantage of being cheap to apply and being free of the potential environmental and health impacts of GM crops or pesticide usage.

'If Africa is to become more self reliant in food supply without locking farmers into very expensive GM seeds and their associated herbicides then the Government need to be funding more projects like 'push pull'.'

A spokesman for the Department for Innovation, Universities and Skills admitted Sir David simply got it wrong.

He said: 'Sir David has said this was an honest mistake.'

Sir David has described the Daily Mail's campaigning stance on GM food as 'brilliant journalism'.

However, he complained it had held up the introduction of GM technology. This line has been rejected by Dr Horton.

Dr Horton praised Sir David for his 'boldness' in persuading the Government to take climate change seriously. However, he criticised his outspoken attacks on the media as 'a sorrowful end to a not undistinguished term of office'.